POST HARVEST DISEASES OF CHILLIES

1. POST HARVEST DISEASES OF CHILLIES

2. Post harvest diseases • Bacterial soft rot - Erwinia carotovora subsp. carotovora • Anthracnose - Colletotrichumcapsici • Fruit rot - Alternaria solani • Gray Mould - Botrytis cinerea • Late blight -Phytophthoracapsici

3. Bacterial Soft Rot- Erwinia carotovora subsp.carotovora Symptoms • Dark veinal tissue followed by leaf chlorosis and necrosis • Internal dark brown discoloration • Stem cankers develop - breakage of branches • Wilting and drying Symptoms on fruits • Fruit peduncle - highly susceptible & is frequently the initial point of infection • Both ripe and green fruit may be affected Post-harvest softening of stem end of fruit

4. Initially, the lesions on the fruit are light to dark-colored, water-soaked, and somewhat sunken • In later stages, bacterial ooze may develop from affected areas, and secondary organisms follow, often invading the rotted tissue • Affected fruit hang from the plant like a water-filled bag Rotting fruit Collapsed fruit

5. Conditions for Disease Development • Transmitted by irrigation water, but a wound is necessary for infection to occur • High rate of nitrogen fertilization is associated with increased susceptibility to soft rot • Post-harvest soft rot of pepper fruit arises when, • infected fruit is harvested with healthy fruit • harvest containers are contaminated with the bacteria • fruit is subjected to contaminated wash water, contaminated surfaces or soil debris

6. Bacterium • Gram –ve, rod shaped bacterium • 1 to 6 peritrichous flagella Epidemiology • Warm, moist weather - highly favorable for infection • Temperature - 25° to 30°C, RH - 95%

7. Disease management • Disease incidence could be reduced by • Early detection of symptoms • Disinfection of pruning tools • Avoidance of wounding plants • Remove plant debris - fallen, diseased leaves • Seed treatment– 1% sodium hypochlorite for 30 sec, then rinse with clean water • Avoid planting pepper crops following crops of potato or cabbage • Rotate instead with crops of bean, corn and soybean

8. Post-harvest disease management • Use chlorinated water to reduce populations of soft rot bacteria and to reduce the risk of infection during washing • Allow fruit to dry thoroughly • During packing and storage, the fruit should be kept clean and maintained in a cool, dry place

9. Anthracnose- Colletotrichumcapsici • Ripe fruits turning red are affected • Small, black, circular spot appears on the fruit skin • Badly diseased fruits turn straw colour or pale white colour, lose their pungency

10. Diseased cut open fruits - lower surface of the skin is covered with minute, elevated sclerotia • Advanced stage - seeds covered by a mat of fungal hyphae, turn rusty in colour Causal Organism - Colletotrichumcapsici • Mycelium - septate and inter and intra cellular • Acervuli and stroma on the stem are hemispherical • Conidia - in mass appear pinkish

11. Epidemiology • Temp - 28oC, RH - 95% • High humid conditions when rain occurs after the fruits have started to ripen Mode of spread & survival • Seed borne • Secondary spread is by air borne conidia & rain • Flies and other insects – responsible for dissemination of the spores from one fruit to another

12. Control measures • Use disease free seeds • seed treatment - thiram 2 kg/ha or zineb 2.5 kg/ha • Three sprayings with captan 0.2 % • 1st spraying - just before flowering • 2nd at the time of fruit formation • 3rd - fortnight interval after second spraying Biocontrol • P. fluorescens, Bacillus subtilis -effective (Rajavel, 2000) • P. fluorescens and T. viride (Muthuraj, 1998) • Saccharomycescerevisiae & P. fluorescens (Jayalakshmiet al., 1998) • Essential oil - Nigellasativa - antimicrobial activity

13. Gray Mould - Botrytis cinerea Brownish spots develop near the soil line or cotyledons Water-soaked lesions on leaves & stems darken and collapse

14. Water-soaked spots that rapidly expand into large yellowish-green or grayish-brown, irregular lesions that are soft and spongy in texture • Velvet-like fungus mycelium and spores are produced on the lesion surface under cool, humid conditions Water-soaked spots collapse

15. Fungus • Botrytis cinerea - abundant hyaline conidia (asexual spores) borne on grey, branching tree-like conidiophores • It overwinters as sclerotia or intact mycelia, both of which germinate in spring to produce conidiophores • The conidia are dispersed by wind and rain-water and cause new infections Conidia and hyphae

16. Favourable conditions and spread • Fungus sporulation and infection, is favored by cool and wet weather • Temperatures of 17–23°C, RH - 90% • Excessive application of nitrogen makes plants such as young transplants more susceptible to gray mold • High canopy density creates conditions for extended leaf wetness at night and subsequent increased gray mold severity

17. Control • Field sanitation - remove and burn decaying infected plant parts • Space seedlings and transplants to allow for free flow of air through the crop • Treatment with hot air at 38oC for 48-72 h or hot water at 50oC to 53oC for 2 to 3 min

18. Alternaria rot- Alternaria solani • Brown lesions surrounded by a yellow halo develop on the fruit • Lesions enlarge and result in the formation of irregular sunken patches with a dark brown margin and light grey centre

19. Fungus • Hyphae - septate, branched, light brown becoming darker with age • Conidia - single, muriform, beaked and dark in color • Source of infection - infected seeds and plant debris Alternaria solani conidia. Note the transverse and vertical septa and the long "beak" (arrow) Spores of A. solani

20. Control • Fortnightly spraying of • Bordeaux mixture 1.0 % • Copperoxychloride 0.3 % • Difolatan 0.3 % • Mancozeb 0.2% • Reduction in the pathogenicity and development of these pathogens in inoculate peppers, • Treatment with hot air at 38oC for 48-72 h • Hot water at 50oC to 53oC for 2 to 3 min

21. Late blight -Phytophthoracapsici • Infected leaf tissue - wilted, light green or gray-green, later becoming tan to white and scalded in appearance • With moisture, leaf spots have a water soaked border • Fruit rots - irregular in shape and olive green or light green with water soaked borders • Rots expand rapidly and fruits can be completely diseased and desiccated, causing the formation of "mummified" fruits • Infected seeds are brown and shriveled

22. Fungus • Produces microscopic, asexual spores called sporangia • Sporangia - spherical to pyriform, hyaline, papillate and have a long pedicel attached to the base of the spore • Pathogen grows well between 25 and 30oC Mode of spread • Survives in the soil in host debris • Roots, stems, and mummified fruits left in the field after harvest, harbor the pathogen for months • Phytophthoracapsici is also seed borne

23. Control • Rotation with non-susceptible crops will reduce the amount of Phytophthoracapsici surviving in soil • Fresh, clean seeds should be planted in new potting mix to establish healthy transplants • Monitor seedlings as well as the field and remove diseased plants as soon as they occur